Video Games Encyclopedia

Flight simulators “tend to fall into military or civilian categories”.
Civilian flight simulator: These games “seldom have any victory conditions, unless they implement racing or specific challenges, such as tests of speed and accuracy”. Still, players can be presented with a variety of challenges including flying at night, or flying in harsh weather conditions. One of the most difficult challenges is to land the plane, especially during adverse weather conditions.
Military flight simulators: Military or combat flight simulators demand that players “achieve the mission’s objectives, usually attacking enemy aircraft and ground installations”. These games depend heavily on the aircraft or role being simulated, where fighter planes largely engage with enemy aircraft, while bombers are designed to attack targets on the ground. A unique aspect of these games is the ability to view ground targets, or view the action from the perspective of a bomb or missile. Players are often confronted with a series of missions with both primary and secondary objectives, and victory is achieved by completing a combination of goals. Many games will also award different levels of victory based on how many objectives were completed, or how much time or damage the player took.
Fantasy flight simulators: in some extraordinary instances, a game will create the experience of flying on fantastical vehicles, such as a dragon.